from __future__ import annotations
import time
from sqlalchemy import text, func

_DB_TYPE: str = "postgresql"


def set_db_type(db_url: str):
    global _DB_TYPE
    _DB_TYPE = "sqlite" if db_url.startswith("sqlite") else "postgresql"


def is_sqlite() -> bool:
    return _DB_TYPE == "sqlite"


def now_expr():
    return text("CURRENT_TIMESTAMP")


def timestamp_ge_expr(column, ts: float):
    if is_sqlite():
        return column >= func.datetime(ts, "unixepoch")
    return column >= func.to_timestamp(ts)


def timestamp_lt_expr(column, ts: float):
    if is_sqlite():
        return func.datetime(column) < func.datetime(ts, "unixepoch")
    return column < func.to_timestamp(ts)


def strftime_expr(format_str: str, column):
    if is_sqlite():
        return func.strftime(format_str, column)
    return func.to_char(column, format_str)